Relatively large bevel gear and pinion sets have long been used in the power trains of heavy duty earthmoving equipment. On large off-highway mining trucks the heavy dynamic loads experienced on such sets have resulted in gear support deflections and tooth deflections which cause non-conjugate contact, which in turn causes the gear tooth tip to improperly engage the pinion in the area of the start of active profile (SAP). This can ultimately result in pitting failure of the teeth.
In order to solve the aforementioned problem the active profile of the large bevel gear was modified on the convex tooth face of each tooth to remove material adjacent the tip. These prior non-generated, tip-relieved spiral bevel gears did result in improvement in the service life of the bevel gear and pinion sets. However, each bevel gear was finished cut on a machine requiring a rotary milling cutter having cutter blades with a preselected special relief profile. This provided a tip relief parallel to the root line that was nonuniform from the toe to the heel thereof. These modified bevel gears required specially designed cutter blades, and both the blades and the gear teeth were difficult to inspect because of the close tolerances required.
Accordingly, what is needed is a spiral bevel gear with a much more uniform tip relief across the tooth face thereof, and a reliable method of manufacturing such a bevel gear without resorting to the need for a modified set of special cutting blades. The more uniform tip relief must result in an improvement in the mating contact pattern with the associated pinion gear and minimal pitting after an extended service period.
The present invention is directed to overcoming one or more of the problems as set forth above.